Bug 302668 : Blank buttons show up in Extension Manager on OS X when updates are available, patch by Robert Strong <rob_strong@exchangecode.com>, r+a=bsmedberg

toolkit/themes/pinstripe/mozapps/extensions/extensions.css

@@ -115,8 +115,8 @@ richlistbox {
   -moz-image-region: rect(52px, 160px, 78px, 128px) !important;
 }
 
-.button-text {
-	display: none;
+#commandBar .button-text {
+  display: none;
 }
 
 .commandBarSeparator {